when i try to uv unwrap my mesh , blender hangs and become unresponsive, why?
Potential Solution: Smart UV Project



Although I've never tested this method on a UV Unwrap task that has crashed Blender, I've found that using the 'Smart UV Project' option is much faster using the normal 'Unwrap' function.

I found this when unwrapping the mesh of an ANT Landscape body, where it would take several unresponsive seconds before Blender processed the unwrap using the regular unwrap function. 
However, when I unwrapped again using the 'Smart UV Project' option (with the default parameters), it was almost almost instantaneous.

I know this is a pretty old post but I'll leave this here just in case anyone finds it and gets help from this answer. (Hope I haven't broken any community forums by 're-opening' an 'archived' thread.)